To be honest with you, my point of view is that no antivirus is going to protect me 100%, I always have to care about what I open, where it's coming from, ...

What I want from my AV then, is to catch the most obvious (and thus numerous) ones, and do so in a way that doesn't bother me. MSE just doesn't get in the way. It updates silently. It scans silently. It detects silently, ask you for something but take the safe course by default. You are in a full screen app ? It doesn't crash everything trying to take control, it just deals with the threat and show a red icon in the tray.

It doesn't make my computer safer than the other, but it makes me lose way less time when it does its job.